Composite piston-packing ring and method of making same



Aug. 28, 1923.

G. CHRISTENSON COMPOSITE PIsToN PACKING RING AND METHOD 0F MAKING SAME Filed Jan. 11

Patented Aug. 2S, 1923.

unirse stares' rattan Parenti ortica.

GEORGE CHRISTENSON, 0F NORTH PLAINFIELD, NEW JERSEY, ASSIGNOR TO JOHNS- MANVILLE INCORPORATED, A CORPORATION OF NEW YORK.

COMPOSITE PISTON-PACKING vRING AND METHOD OF MAKING SAME.

Application filed January 11, 1921. Serial No. 435,445.

To all whom it may concern:

Be it known that I, GEORGE CHRrsTENsoN, a citizen of the United States of America, residing at North Plainfield, county of Somerset, and State of New Jersey, have invented certain new and useful Improvements in Composite Piston-Packing Rings and Methods of Making Same, of which the fol lowing is a specification.

My invention 'relates to the formation of composite rings which are suitable for use as cup-shaped packing for pistons Where great toughness and durability is required, as in the case of packing for pistons in airbrake cylinders. v

According to my invention these rings are formed of a body of plastic vulcanizable material spread upon a sheet of textile fabric and the composite body so formed folded upon itself, shaped into a ring and molded and vulcanized under pressure, with the result that the textile fabric is distributed more of less through the body of the vulcanized material forming the major portion of the ring, said textile fabric serving as astrengthening skeleton therefor.

One embodiment ofmy invention and of the apparatus and materials for making the same, is illustrated in the accompanying sheet of drawings, in which Fig. 1 is a cross section of one form of blank from which the completed ring may be made, part being broken away;

Fig. 2 is a similar view of a modified form of blank;

Fig. 3 is a. cross section of a mold for changing the shape of the blank, parts being broken away;

Fig. 4 is a similar view of a Vulcanizing mold; andA Y Fig. 5 is a perspective Viewl of a segment of the completed ring.

Throughout the drawings like reference characters indicate like parts.

1 is a layer of plastic Vulcanizable material, such as that set forth in my U. S. Patent No. 1332320, issued March 2nd, 1920, which is spread upon any suitable. textile fabric 4. Preferably the textile fabric should be a -fairly coarse, strong asbestos lcloth. The composite structure so formed having been cut into strips of the proper size is folded one or more times upon itself and the abutting ends of the folded strip fastened together to form a ring of proper diameter. These strips may be folded so as to bring the fabric 4 on the inside, if only a double fold is employed, as shown in Fig.

1, or may be folded so as to bring the fabric on the outside of the ring, as shown in Fig. 2.

The ring so ,formed is then shaped or molded into the desired form for cup-packingy or other purpose forwhich it is designed, and vulcanized under pressure in this shape.

Preferably in forming piston packing I first compress the blank between the curved tion to the proper degree of heat to vulcanize the plastic material, the ring may be removed, producing thel completed packing ring 7 shown in Fig. 5. y

In the completed packing ring the textile fabric is imbedded and more or less disseminated by the-action of the plastic material which has been forced between the threads of the fabric by the great pressure of the molds, and the textile fabric thereby becomes a supporting skeleton for the'- completed ring, which adds greatly to its toughness and tensile strength and its resistance to wear.

This fabric arranged as a skeleton in the ring is indicated at 4 in Figs. 3, 4 and 5, the arrangement being that which would be produced by operating on the form of blank shown in Fig. 1.l Ofcourse if the blank shown in Fig. r2-were employed, the two sectionsrof the skeleton fabric would be somewhatmorepseparated and located nearer the external surfaces of the completed packing ring.

Of course more than two folds of the original fabric might be employed in making the rings, if desired, and other means of molding or shaping the same might be employed.

I claimt 1. The method of forming a composite ring suitable for use as a cup-shaped piston packing or the like, which comprises the following steps: first, applying to a sheet of woven fabric a layer of plastic material capable of being vulcanized of a greater thickness than that of the fabric; second,

folding the composite fabric so formed upon L@ d meerder itself and arranging such folded fabric in en as e cup-shaped iston-packing er the like, 10 annular form; third, molding said ring intocomposed cfa. re @tively thick mess of Vulthe desired shape and vulcmzing the plastic' canized material having e, folded sheet of material, wherebyl the textile material berelatively thin textile fabric imbedded 5 comes imbedded in the vulcanized mess and therein.

Y forms a, skeleton support therefor in wrele- GRGE CHRSTESON. tively thick completed ring. l Witnesses:

2. A product of the herein described proel P. lil. REDDING,

ess, being e composite ring suitafble for use WM. ALLMAN, 

